Contstraint effects of shallow cracks in structures containing fillet weld toe cracks

Abstract

Current methods for determining fracture toughness values for structures containing weldments rely on homogeneous models. This research invalidates this assumption by using finite element analysis results to calculate applied J values for structures containing a/W--O.l and a/W--O.5 fillet weld toe cracks. The Anderson-Dodds scaling model is applied to quantify the effects of finite size on J contour integral values for structures containing a/W=O.l and a/W=0.5 fillet weld toe cracks loaded in bending and in tension. The negligible effect of material mismatch for the aforementioned structures containing 20% overmatched weldments (weld material stronger than parent material), and 20% undermatched (parent material stronger than weld material) weldments is also shown via application of the AndersonDodds scaling model. The Anderson-Dodds scaling model relies on the assumption that a constant scaling parameter exists between the finite body and infinite body J contour integral values. Hence, as this assumption breaks down the Anderson-Dodds scaling model becomes invalid. This study shows that the Anderson-Dodds can be applied to most of the non-symmetric geometries analyzed without significant error, but that a symmetry causes it to break down for the case of a structure containing and a/W=O.l fillet weld toe crack loaded in tension.